A combustion turbine power plant is the power plant of choice for supplying peak power. For an overwhelming majority of electric power customers (in the U.S. and abroad) power consumption reaches its peak during the summertime, the time when the power production of combustion turbines is at its lowest, due to high ambient temperature. The simplified explanation of the reduced power production is that the high ambient temperature with associated lower inlet air density, reduces mass flow through a combustion turbine assembly with a respective reduction of the power produced. FIGS. 1a, 1b, and 1c present simplified heat and mass balances of a conventional General Electric Frame 7 EA combustion turbine assembly 12 operating at three ambient temperatures: 59 F (FIG. 1a), 0 F (FIG. 1b) 90 F (FIG. 1c). The combustion turbine 12 includes a compressor 14, an expansion turbine 16, a combustor 18 which feeds heated combustion product gas to the expansion turbine 16. The expansion turbine 16 is coupled to drive the compressor 14 and an electric generator 20, which is coupled to the electric grid 17.
FIGS. 1a-1c demonstrate that the conventional General Electric combustion turbine assembly, rated at 84.5 MW at ISO conditions (59 F with 60% relative humidity), will produce maximum power of approximately 102.5 MW when the ambient temperature is 0 F, and will drop power to approximately 76.4 MW at 90 F. The significant power loss by a combustion turbine assembly during high ambient temperature periods requires a utility to purchase additional peak capacities to meet summer peak demands. Power loses for a combined cycle power plant operating at high ambient temperatures are similar to those of combustion turbine assemblies.
There are conventional methods to partially restore the loss power of combustion turbines/combined cycle plants during high ambient temperature periods: evaporative cooling and various combustion turbine inlet air chillers (mechanical or absorption type). These methods result only in partial restoration of combustion turbine power while significantly increasing capital costs, which is not always justified for an operation limited to time periods with high ambient temperatures.
Accordingly, there is a need to develop a method which will allow a combustion turbine assembly to operate at maximum power, regardless of ambient temperature.
Similar power loss problems exist in the case of a combustion turbine assembly installed at high elevation. The problem in these applications is associated with lower air density and a corresponding loss of consumption turbine power. There are currently no methods to restore power loss associated with high elevation applications.
Accordingly, a need exists to develop a method which will allow a combustion turbine assembly to maintain maximum power even when operating at high elevations.